Glow-discharge transmitter



J. SLEPiAN GLOW DISCHARGE TRANSMITTER Filed Oct. 28, 1922 mws; i

mm J \NEKQ INV'ENTOR Patented May 3, 1927.

UNITED STATES.-

PATENT. or IcE.

JOSEPH SLEPIAN, OF SWISSVALE, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSEELECTRIC do MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

GLOW-DISCHARGE TRANSMITTER.

Application filed October 28, 1922. Serial No. 597,562.

y invention relates to telephone systems and apparatus and particularlyto telephone transmitters One object of'my invention is to provide 5' atranslating device, of the class described,

wherein sound waves are faithfully translated into correspondinglymodulated electrical energy without impairing the quality,

tone and quantity of the translated energy.

Another object of my invention is to provide a sound-translating deyiceand circuit connections therefor which insure the translation of soundwaves into correspondingly modulated currents without the introductionof distorting harmonics.

' .Still another object of my invention is to provide telephonetranslating apparatus which embodies no moving parts and, moreespecially, one wherein the usual vibratory diaphragm may be dispensedwith.

A still further object of my invention is v to provide a translatingdevice. of the class described. which is characterized by its simplicityof design and operation and which lends itself to inexpensiveconstruction and manufacture, the several parts of which may be easilymade on existing automatic machinerv and may readily be assembled with aminimum expenditure of time and money. According to my invention. Iprovide a sound-wave translating device employing a pair ofspacedelectrodes in the air or other medium subject to pressure variationsfrom the sound waves to be translated, together with means forestablishing. between said electrodes. a glow discharge of a particularcharacter hereinafter described. and means for detecting or utilizingthe changes in the characteristics of the discharge resulting from theatmospheric pressurevariations. In certain types of glow-dischargeapparatus. among which may be m'entioned those in .which the anode is soclose to the cathode that the positive column and the 4 Faraday darkspace is substantially absent from the glow-discharge. the discharge maybe susceptible of covering not only the extreme end of the cathode butalso a variable amount of the side surfaces, dependent upon pressureconditions. Under such circumstances. the voltage-drop across thedischarge is ordinarily independent ofsmall pressure variations in thesurrounding medium. I have found, however, that when the availablecathode surface is completely covered by the discharge, so that the areaof cathode surface covered by the discharge cannot change with varyingpressure conditions, and when the current through the discharge ismaintained substantially constant, the voltage drop varies directly withthe pressure, for slight pressure variations,

\Vhile the discharge device just mentioned has been referred to as atranslating device, it is, in reality, also an amplifying device,inasmuch as a source of energy, say, the sound waves, controls theconstants of a circuit embodying a considerably larger source of energy.

Although the primary object of my invention is to provide a translatingdevice for sound waves, it is apparent that my invention embodiescertain distinctive features and characteristics which make itapplicable to other uses, as will be apparent to those skilled in theart.

Withthese and other objects and applications in view, my inventionfurther consists in the nature. the mode of operation and theconstructional details hereinafter described and claimed and illustratedin theaccompanying drawing, wherein: Figure 1 is a View, partiallydiagrammatic and partially structural, of circuits and apparatusembodying a preferred form of my invention,

Fig. 2 is a greatly enlarged detail view of the discharge electrodes ofFig. 1, illustrating the maximum number of component 'ing amodification.

In the illustrated embodiment-of my invention shownin Fig. 1, a pair ofspaced electrodes 1 and 2having discharge surfaces 3 and4. respectively.are connected by conductors 5 and 6,t the'plu and minus ter-- minals ofa source 7 of d rect-current energy. A resistor 8. which serves tostabiliz e the current through the discharge and to hold the samesubstantially constant, may be connected in series-circuit relation withthe conductor 6. In practice, it has been found that the energy sourcemay have an electromotive force on the order of 6000 volts and theresistance of the resistor 8 may be on the order of a megohm.

For purpose of illustration, I have shown one arrangement for limitingthe available discharge surface of the negative electrode the cathodeglow space 13 are 2, though my invention is not to be limited thereto.The arrangement comprisesthe conducting element 2, which is made ofplatinum or other suitable material and which is fused in the axis of acylindrical mass of glass 9 having a substantially fiat surface 11 atoneend. The end of the mass of glass is ground flush with the end of .saidelectrode 2, thus providing a construe tion wherein the exposeddischarge surface 4 is limited to such portion of the conducting element2 as is disposed in the flat-end surface 11} of the glass member 9.

When the electrodes are separated a certain amount, say, of an inch, fora system embodying the constants indicated, a glow discharge may beformed between the two electrodes land 2 following portions tween thenegative electrode 2 and the positive electrode 1: a cathode glow 12,which is.

in immediate contact with the negative electrode 2, a cathode dark space13, sometimes known as Crookes dark space, a negative light 14, theFaraday dark space F, and a positive or anode column C, which terminateson the positive electrode 1, all as indicated ona much enlarged scale inFig. 2.

In my invention, however, the electrodes 1 and 2 are preferably broughtcloser together than the distance which will produce allof thecharacteristic parts shown in Fig.

2, so that the positive column C and the 1 of this specification, it hasbeen observed that, when the negative light 14 completely covers theavailablcathode surface 4, and when the current therethrough ismaintained substantially constant, the potential drop across theelectrodes 1 and 2, or, to be more specific, the so-called cathode drop,or potential drop between the cathode and the free boundary-of thecathode glow, va-

ries inversely with the atmospheric pressure. Hence, when the pressurein the immediate vicinity of the discharge is varied, as by thepresenceof sound waves, the potential drop across the electrodes 1 and 2 isvariedin accordance with the varying intensity thereof. The potentialdrop across the electrodes 1 and 2 is thus composed of a constantcomponent, namely, the so-called quiet voltage drop and an alternatingwhich comprises the arranged 1n order be-' ing such component which, asjust stated, corresponds in intensity with the varying intensity of thesound waves. The alternating 'component of voltage ]ust mentioned may betranslated into amimpressing the same through conductors 15 and 16 uponthe grid-filament elements 17 and 18, respectively, of a three-electrodevacuum tube 19, including, in addition, a plate element 21.

plified currents of similar wave form by A condenser 22 havinganegligible iinpedance to sound waves of the lowest frequency isincluded in the conductor 15 and serves to prevent the so-called quietvoltage drop across the electrodes 1 and 2 from operating to efiect theblocking of the tube 19. A grid-leak resistor 23 may be connected inshunt relation to the grid-filament elements 17 and 18 of the tube 19 inorder to control the intensity of the negative charges which areaccumulated on the grid 17 during the operation of the tube 19.

A plate-filament circuit for the tube 19 includes a source 24 ofdirect-current energy and a coupling coil 25, the latter beingoperatively. coupled to a second coupling coil 26 which is-seriallyincluded .in an outgoing or work circuit 27. The work circuit 27 may, inturn, circuit arrangement designed to employ modulated currents.

be connected in any.

In summary, the operation of my inven- I tion, as shown in Fig. 1, is,briefly, as follows: Withthe formatlon of a glow dis charge between theelectrodes 1 and 2 havproportions thatthe cathode glow 14 completelycovers the available cathode surface 4, the potential drop, or, to bemore specific, the so-called cathode drop, Va-

rice in accordance with the varying iuten-' sity of such sound waves asare caused to impinge thereon.

The resulting alternating component of voltage is impressed upon theinput electrodes 17 and 18 of the repeater device 19, causing thepassage of relatively heavy currents having correspondingcharacteristics in the plate-circuit of the device 19. Theamphfiedcurrents may, 1n turn, be further impressed upon the workcircuit 27 which is associated with other circuits and apparatus notshown.

The arrangement shown in Fig. 3 is dif ferentiated over that shown inFig. 1 in the provision of a supply circuit for the discharge electrodes1 and'2 having such low impedance that current variations areestablished therein, when the pressure 11) the vicinity of the dischargeis varied, rathervariations, as in Fig. 1. ,The supply circuit for thedischarge electrodes 1 and 2 now includes a low-voltage source 28 ofdirect-current energy. and the primary winding 29 of a transformer 31for translating the current variations in the supply than potential madein the nature,

circuit to potential variations across the terminals of the secondarywinding 32 of said transformer. The potential variations may betranslated into amplified current variations in the same way asindicated in Fig. 1. The operation of this tigure is otherwise asindicated for that of Fi 1,

In 3, have illustrated the cathode 2' as extending slightly beyond theend surface 11 of the glass, the cathode glow 14; being illustrated asapparently covering the entire exposed surface of the cathode, ashereinbefore explained.

While I have described my invention as embodied in circuit arrangementshaving certain specific values, it is to be understood that my inventionis not to be limited thereby. Furthermore, it is apparent that various.changes and modifications may be the mode of operation and theconstructional details thereof 'without departing from the spirit of myinvention. I desire, therefore, that only such limitations shallbeimposed thereon as are indicated in the appended claims or demanded bythe prior art. I

I claim as my invention:

1. A sound-responsive device including a pair of spaced electrodes'opento the atmosp: ere, therebetween and means controlled by the electricalchanges in said glow-discharge produced by sound for producing an outputrepresentative of said sound.

2. A sound-responsive device including a pair of spaced electrodes opento the atmosphere, means for causing a glow-discharge therebetween andmeanscontrolled by the electrical changes in said glow-dischargeproduced by sound for producing an output representative of said sound,and means associated with one of said electrodes for -limiting theavailable discharge. surface thereof.

3. A sound-responsive deviceincluding a pair of spaced electrodes opento the atmosphe're, means for causing a glow-discharge therebetween andmeans controlled by the electrical changes in said glow-dischargeproduced by sound for producing an output representative of said sound,means associated with one of said electrodes for limiting the availabledischarge surface thereof, said discharge-causing means maintaining thedischarge at sutficient dimensions to cover said available dischargesurface.

4. In a sound-responsive device, a positive electrode and a negativeelectrode open to the atmosphere, means for limiting the availabledischarge surface of the negative electrode,

: means for establishing a glow-discharge between said electrodes, thedistance between said electrodes having such a relation to thesaiddischarge-establishing means that the glow-discharge comprises mainly anegative means for causing a glow-discharge,

subject to electrode and a negative electrode exposed to, atmosphericpressure. said'ncg'ativc electrode comprising a conducting element and anon-conducting element, said elements being flush with each other,whereby an exposed discharge surface of limited are'a'is provided, andmeans for establishing'a glowdischarge between said electrodes,- thedistance between said electrodes being so short that'the Faraday darkspace and positive column if present together constitute less than afourth of said-distance. andsaid discharge-establishing meansmaintaining the glow-discharge of such magnitude that the said limitedarea is completely coveredby the cathode glow.

6. In a sound responsive device, a positive electrode and a negativeelectrode exposed to atmospheric pressure, said negativeelectrode'comprising a conducting element and a non-conducting elementsurrounding it,

the end surfaces of said elements being flush with each other, wherebyan exposed discharge surface of limited area is provided and means forestablishing a glow-discharge between said electrodes, the distancebetween said electrodes being so short that the glowdischarge issubstantially without a Faraday dark space or a positive column and saiddischarge-establishing means maintaining the glow-discharge of suchmagnitudethat the said limited area is completely covered by the cathodeglow. 7. In combination, an electrical circuit including a pair ofspaced electrodes, means for establishing a glow discharge between saidelectrodes having such proportions as to cover the available dischargesurface of one of said electrodes, means for causing the the presenceofsound waves, and means for translating the effects resulting fromvariations in the characteristics of said discharge into amplifiedcurrent variations.

8. A sound-Wave translating device'comprising a cathode and an anode ina medium pressure variations in the presence of sound waves, means forestablishing, between said cathode and said anode, a glow dischargeincluding a cathode glow whereby the potential of said cathode glowrelative, to the cathode will vary with varying pressure, and atranslating device responsive to said variations in said relativepotential.

9. A sound-wave translating device com prising a pair of spacedelectrodes in the air, means for establishing therebetween a glow 4.1,a2e,eae

' discharge including negative light extend-, 11. The method ofdetecting movements in ing substantially from oneelectrode'to the afluid non-conducting medium which conother, means for causing thedischarge to sists in maintaining an electric glow-dis- 20 cover, at alltimes, a, substantially constant charge therein and detecting thechanges in cathode area notwithstanding pressure .vaa characteristic ofthe discharge resulting riations due to sound waves impinging therefromsaid fluid movements.

upon,an'd means responsive to the variations 12. A device for detectingmovementsin in an electrical quantity of said discharge in a fluidnon-conducting medium comprising 2 the presence of sound WAVES; meansfor maintaining an electric glow-dis- 10. The method of converting soundwaves charge therein and means for detecting the into variations ofelectric current which conchanges in a' characteristic of the dischargesists inestablishing a glow discharge includresulting from said fluidmovements.

ing a cathode glow havin a variable poten In testimony whereof, I havehereunto tial relative to the catho e dependent upon subscribed mynamethis 25th day of Ocpressure variations in the surroundingmetober,'1922. dium, and detecting the resultant variations in anelectrical quantity of said discharge. M JOSEPH SLEPIAN.

